Infants with peroxisomal disorders, including Zellweger's syndrome and infantile adrenoleukodystrophy, commonly have liver disease because of impaired peroxisomal metabolism and accumulation of bile acid intermediates. Using techniques of mass spectrometry, electron microscopy and MRI-spectroscopy, this study is evaluating the role of bile acid therapy (cholic acid) as therapy for the liver disease in peroxisomal disorders of infancy.